Chung's delegation had been set to return to Seoul on Friday morning but was told to remain because Kim wanted to meet them.

Hopeful meeting

The reclusive Kim last met a top South Korean official in the North's capital in April 2002, before the nuclear crisis erupted later that year after US officials accused Pyongyang of running a secret uranium enrichment programme.

Kim rarely meets visiting officials, and the meeting raised hopes in the South of possible movement in the latest nuclear crisis.

"It shows North Korea is making their best efforts," South Korean Prime Minister Lee Hae-chan said in Seoul.

The North has refused to return to the nuclear disarmament talks for nearly a year, citing "hostile" US policies, and declared itself a nuclear state in February.

It has also in recent months made moves that would allow it to create more weapons-grade plutonium, adding to a stockpile experts believe is already enough to build about six nuclear bombs.